1. Field of the Invention
The present invention relates to a method of and an apparatus for laminating a plurality of endless metal rings.
2. Description of the Related Art
Power transmitting belts for use in continuously variable transmissions for automobiles comprise a plurality of elements stacked in an annular array and bundled by laminated rings for endless circular motion. Each of the laminated rings comprises a plurality of endless metal rings having a predetermined axial width and also having respective different circumferential lengths. The endless metal rings are laminated successively in the order of increasing circumferential length from the outer circumferential side toward the inner circumferential side.
It has heretofore been customary to laminate the metal rings by manually fitting each metal ring, which is held in the shape of a substantially true circle, in an adjacent metal ring against its inner circumferential surface successively in the order of increasing circumferential length. However, the manual fitting process cannot easily be performed because the difference between the circumferential lengths of outer and inner metal rings to be fitted together is very small in order to produce a highly accurate laminated ring that comprises metal rings stacked closely together. If an attempt is made to manually fit the metal rings roughly without sufficient care, then the metal rings tend to be damaged when they contact each other, and when the resultant power transmitting belt is used, its efficiency to transmit power is liable to decrease and the laminated ring is apt to be broken.
Japanese laid-open patent publication No. 63-281725 discloses a process of laminating metal rings which has been proposed to eliminate the above drawbacks. According to the disclosed process, an annular metal ring is pressed radially inwardly toward its center by three presser rods to form radially inwardly projecting curved regions, thus deforming the metal ring into a shape having a smaller diameter than its original diameter. The deformed metal ring is then released from the presser rods to restore its original shape within another annular metal ring, so that the two metal rings are laminated to each other.
Since the inner metal ring and the outer metal ring do not contact each other until the inner metal ring restores its shape within the outer metal ring, the metal rings are prevented from being damaged by any manual fitting process which would otherwise have been carried out.
However, since the proposed process needs to repeat a cycle of deforming an inner metal ring into a smaller-diameter shape, placing the deformed metal ring into an outer metal ring, and then laminating the inner metal ring to the outer metal ring, the process tends to be time-consuming and poor in efficiency if the number of metal. belts to be laminated is relatively large.
It is therefore an object of the present invention to provide a method of and an apparatus for laminating a plurality of metal rings efficiently in a short period of time even if a large number of metal rings are to be laminated.
To achieve the above object, there are provided in accordance with the present invention a method of and an apparatus for laminating a plurality of endless metal rings having different respective circumferential lengths successively in the order of increasing circumferential length from the outer circumferential side toward the inner circumferential side. The method comprises the steps of holding the metal ring of the greatest circumferential length in the shape of a substantially true circle and holding the other metal rings in an array successively in the order of increasing circumferential length toward the metal ring of the greatest circumferential length in a transverse direction of the metal ring of the greatest circumferential length, inserting at least three holder rods, which are spaced from each other and extend parallel to each other, into the metal rings along the array thereof to hold the metal rings in substantially coaxial alignment with each other, while holding the metal rings from inner surfaces thereof with the holder rods, pressing at least three presser rods, which are disposed in respective locations corresponding to spaces between the holder rods, from outside of the other metal rings through the spaces between the holder rods toward the center of the metal rings, thereby deforming the other metal rings resiliently into a shape including curved portions projecting radially along the holder rods and having a reduced diameter, and delivering the deformed metal rings successively in the array along the presser rods from terminal ends of the presser rods into a position in which the metal ring of the greatest circumferential length is held, and releasing the deformed metal rings successively off the presser rods within the metal ring of the greatest circumferential length to allow the released metal rings to successively restore a shape of a substantially true circle along an inner circumferential surface of the metal ring of the greatest circumferential length and to be successively laminated to the metal ring of the greatest circumferential length.
With the above method, before the metal rings are laminated, the metal rings other than the metal ring of the greatest circumferential length are arrayed in the order of increasing circumferential length toward the metal ring of the greatest circumferential length, and the arrayed metal rings are simultaneously pressed into the deformed shape by the presser rods. Then, the deformed metal rings are delivered successively in the array off the terminal ends of the presser rods, and resiliently restore to their original shape successively in the order of increasing circumferential length within the metal ring of the greatest circumferential length, whereupon the metal rings are laminated to the metal ring of the greatest circumferential length. Therefore, all the metal rings can be successively laminated in a short period of time with a highly increased efficiency.
According to the present invention, there is also provided an apparatus for laminating a plurality of endless metal rings having different respective circumferential lengths successively in the order of increasing circumferential length from the outer circumferential side toward the inner circumferential side, comprising an assembly holder for holding the metal ring of the greatest circumferential length in the shape of a substantially true circle, an array holder for holding the other metal rings in an array successively in the order of increasing circumferential length downwardly in the assembly holder toward the metal ring of the greatest circumferential length in a transverse direction of the metal ring of the greatest circumferential length, at least three holder rods, which are spaced from each other and extend parallel to each other, vertically movable toward the array holder for being into the metal rings along the array thereof to hold the metal rings in substantially coaxial alignment with each other when the holder rods are lowered, at least three presser rods for pressing the metal rings from outside of the metal rings in the array holder through spaces between the holder rods toward the center of the metal rings, thereby deforming the metal rings in the array holder resiliently into a shape including radially projecting curved portions held by the holder rods and having a reduced diameter, and delivery means for delivering the deformed metal rings in the array holder successively in the array toward the assembly holder and releasing the deformed metal rings successively off the presser rods.
With the above apparatus, the metal rings arrayed in the array holder are aligned by the holder rods to allow the presser rods to press the metal rings with high accuracy. The presser rods press the metal rings between the holder rods to reliably form the curved portions along the holder rods in the metal rings. Therefore, the metal rings can sufficiently deformed into the shape having the reduced diameter.
The apparatus further comprises a limit plate for limiting the presser rods by abutting against the presser rods when the presser rods press and deform the metal rings, the limit plate being disposed inwardly of the holder rods in an upper portion of the array holder. The limit plate allows the presser rods to deform the metal rings quickly to the desired shape having the reduced diameter.
When the metal rings are delivered by the delivery means, the metal rings are reliably kept in their array by being guided by the presser rods, and accurately delivered in the array off the terminal ends of the presser rods.
Because the holder rods are vertically movable, they may be lifted out of the metal rings when the metal rings are delivered by the delivery means. With the holder rods lifted out of the metal rings, any sliding resistance applied to the metal rings is reduced when the metal rings are delivered by the delivery means.
According to a first aspect of the present invention, the delivery means comprises a plurality of vertically movable abutment members movable along upper edges of the metal rings held in the array holder, lifting and lowering means for lifting and lowering the abutment members in unison with each other by a distance required to deliver the lowermost one of the metal rings in the array holder off terminal ends of the presser rods, and displacing means for retracting the abutment members which have been lowered by the lifting and lowering means in unison with each other away from spaces between the metal rings and inserting the abutment members which have been lifted by the lifting and lowering means in unison with each other into the spaces between the metal rings.
With the delivery means according to the first aspect, the displacing means moves the abutment members along the upper edges of the metal rings arrayed in the array holder. Then, the abutment members are lowered in unison with each other by the lifting and lowering means. The upper edges of the metal rings abut against the abutment members, and are moved downwardly. When the lowermost metal ring in the array holder is pushed off the presser rods, the downward movement of the abutment members by the lifting and lowering means is put to a stop. Then, the abutment members are retracted away from the metal rings by the displacing means, and thereafter lifted to their original positions by the lifting and lowering means. The displacing means moves the abutment members toward the array holder. The above operation is repeated until all the metal rings are delivered off the terminal ends of the presser rods.
Since the displacing means of the delivery means according to the first aspect moves the abutment members in unison with each other, the distance that the lifting and lowering means vertically moves the abutment members can be relatively small, making the apparatus compact.
According to a second aspect of the present invention, the delivery means comprises a plurality of vertically movable abutment members movable along upper edges of the metal rings held in the array holder, lifting and lowering means for lifting and lowering the abutment members in unison with each other by a distance required to deliver the uppermost one of the metal rings in the array holder off terminal ends of the presser rods, and displacing means for retracting the abutment members which have been lowered by the lifting and lowering means to deliver the metal ring off the terminal ends of the presser rods, away from following metal rings.
With the delivery means according to the first aspect, the displacing means moves the abutment members along the upper edges of the metal rings arrayed in the array holder. Then, the abutment members are lowered in unison with each other by the lifting and lowering means. The upper edges of the metal rings abut against the abutment members, and are moved downwardly. When the lowermost metal ring in the array holder is pushed off the presser rods, only the abutment member that has pushed the metal ring is retracted away by the displacing means. Then, the abutment members are lowered in unison with each other. When the following one of the metal rings is pushed off the presser rods, only the abutment member that has pushed the metal ring is retracted away by the displacing means. The above operation is repeated until the lifting and lowering means lowers the abutment members until the uppermost metal ring having the smallest circumferential length in the array holder is pushed off the presser rods by the abutment member. Thereafter, all the abutment members are lifted to their original positions while they are being retracted.
Since the displacing means of the delivery means according to the second aspect retracts the abutment members successively from the lowermost one thereof while the abutment members are being lowered by the lifting and lowering means, all the metal rings can successively be deliv ered from the presser rods in one cycle of downward movement of the abutment members. Thus, the metal rings can be laminated in a very short period of time.
In the first and second aspects of the present invention, the abutment members preferably comprise plates arrayed in the array holder and horizontally movable between the metal rings which have been deformed by the holder rods and the presser rods, the plates having clearance recesses to avoid interference with the holder rods and the presser rods when the plates are displaced by the displacing means.
According to a third aspect of the present invention, the delivery means comprises an abutment member vertically movable in abutment against an upper edge of the uppermost one of the metal rings held in the array holder, and lifting and lowering means for lifting and lowering the abutment member to deliver the metal rings in the array in unison with each other successively from the lowermost one of the metal rings off terminal ends of the presser rods.
With the delivery means according to the third aspect, the abutment member is held in abutment against the upper edge of the uppermost metal ring held in the array holder, and is lowered by the lifting and lowering means. Therefore, the metal rings in the array are lowered in unison with each other, and delivered successively from the lowermost one of the metal rings off the terminal ends of the presser rods.
Because the metal rings can be delivered only upon the downward displacement of the abutment member by the lifting and lowering means of the delivery means according to the third aspect, the metal rings can be laminated in a very short period of time, and the apparatus can be constructed simply and inexpensively.
The above and other objects, features, and advantages of the present invention will become apparent from the following description when taken in conjunction with the accompanying drawings which illustrate preferred embodiments of the present invention by way of example.